Embodiments of the invention generally relate to a propeller system of a rotary wing aircraft, and more particularly, to a system for controlling the pitch of a variable pitch propeller system of a high-speed rotary wing aircraft.
A rotary wing aircraft with a coaxial contra-rotating rotor system is capable of higher speeds compared to conventional singe rotor helicopters due in part to the balance of lift between the advancing sides of the main rotor blades on the upper and lower rotor systems. To still further increase airspeed, supplemental translational thrust is provided by a translational thrust system, such as a propeller system oriented substantially horizontal and parallel to the aircraft longitudinal axis to provide thrust for high speed flight.
The thrust generated by the translational thrust system is affected by varying the pitch of the propeller blades individually as the rotor rotates and by varying the pitch of all of the blades together. The translational thrust systems of conventional rotary wing aircrafts include a two way switch configured to control the pitch of the propeller blades. An operator of the aircraft applies a force to one side of the switch to incrementally increase the pitch in a positive direction and applies a force to a second side of the switch to incrementally increase the pitch in a negative direction. Because the switch is continually biased back to the center, the operator must track how many times each side of the button was pressed to have an idea of the pitch angle of the propeller blades.
Therefore, a need exists for an improved control for adjusting the pitch angle of a propeller system which can more efficiently indicate to an operator of the rotary wing aircraft the current pitch angle.